We upgraded all of these from 0.10.0 to 0.10.2 and that fixed the problem we were having.
“@dfinity/agent”: “0.10.2”,
“@dfinity/auth-client”: “0.10.2”,
“@dfinity/authentication”: “0.10.2”,
“@dfinity/candid”: “0.10.2”,
“@dfinity/identity”: “0.10.2”,
“@dfinity/principal”: “0.10.2”
Would still love a report back from someone at Dfinity on this one though.